Such apparatus is known from the prior art. For example, there is available such apparatus which consists of a conveyor trough and a conveyor pipe which are located coaxially one behind the other and within which a transport helix is rotatably driven. The transport trough of this previously known apparatus consists of a sieve plate having a semi-circularly curved cross-sectional shape. The helix is so positioned in the sieve plate that solid components deposited on the sieve plate are transported by the helix in the axial direction of the apparatus and are discharged at a discharge end of the apparatus. Such devices are used in communal and industrial water treatment installations, in paper manufacturing, slaughter houses, fish and food industry plants, textile factories, tanneries, chemical and pharmaceutical industry plants or sewage disposal plants. The purpose of such apparatus is to carry out fine filtering of waste water, slurry sieving or flotation screening. However, by means of such apparatus there also is feasible the cleaning of process and recycling water, the conditioning of cooling water, or the recovery of raw materials. To this end the above-described apparatus is positioned in a trough which device extends generally horizontally with a slight downward slope, the width of the trough generally corresponding to the cross-section of the transport trough. The transport trough extends to the base of the trough. The fluid which is to be cleaned flows through the perforated sieve surface, while the coarse and fibrous material contained in the fluid stream are retained in the sieve portion of the transport trough. The sieve portion of the transport trough is cleansed by the adjacent helix. The washing effect achieved by this technique has the effect that organic components, for example, remain largely present in the water, whereas solid components in the form of impurities are removed. The helix transports the sieved material through the transport pipe to an outlet where the removed solid components can be packed in bags, for example.
A disadvantage of this known apparatus is that only relatively small quantities of fluid can be processed, because the diameter of the transport trough relative to the helix or worm cannot be made arbitrarily large due to manufacturing considerations. Consequently the effective sieve surface is dependent upon the structurally determined limitation of the helix, or worm diameter. It has also become apparent that the tolerances between the helix or worm and the transport trough or transport pipe increase as the diameter of the worm or helix increases. However, with increasing tolerances the output capacity of the above-mentioned apparatus becomes inadequate. Due to large tolerances, only a fraction of the solid components is removed, while a large part of the solid components remains on the sieve surfaces and clogs these, so that the apparatus has to be shut down and cleaned. Practical dimensions of such a worm or helix, or of the trough into device which these components extend, range up to a diameter of 600 mm. Due to these dimensions and the rate of rotation of the helix or worm the operating capacity of such apparatus is limited so that only a predetermined quantity of fluid flow can be treated during a given time period.